1. Technical Area
The present invention relates to systems with a carrier of data, e.g. in the form of a card, which is intended to be inserted into a data reader. In particular, the invention relates to a method of prolonging the time for a contact connection between a card, e.g. a so-called smart card or another card that has a readable and writeable memory, and a reader/writer for the card.
2. Description of the Prior Art
In many situations today, e.g. for checking and identification to allow access to areas, places of work, equipment and similar, magnetic cards are frequently used as carriers of information. These cards (keys) are intended to be inserted in readers (locks) to allow access for those authorized during a certain time and under certain conditions. It is also known to use a so-called smart card (chip card) as a carrier of information, whereby such cards include both readable and writeable memories, which means that the user can thus receive and provide (with the help of a keyboard) different messages about periods of applicability, codes, accounts, errors, etc. The card and reader are arranged so that data can be transferred from card to reader and vice versa by means of an electrical contact connection. One can thus use the card as a communication link between the reader and a central unit, whereby the central unit can be free-standing (off-line) or directly connected (on-line).
One problem of writing, i.e. registering data in a permanent or temporary manner in a memory, on a smart card that is inserted in a reader is that a cycle of writing on the card must be concluded once it has begun. If the cycle of writing is not concluded, one could get corrupted data on the card. A cycle of writing takes about 5-10 ms to perform and if the supply of current is broken during this time, incorrect data can be written on the card. There must thus be an electrical contact connection between the card and the reader during the whole writing cycle.
To ensure that the writing cycle has time to be completed before the contact with the card is broken, one has previously been forced to xe2x80x9clockxe2x80x9d the card in the reader in some way. For example, one has withdrawn the card fully into the reader so that it is not available to the user, or one has held the rear edge of the card with a locking mechanism or physically locked the card in some other way. Such mechanisms are complicated, bulky and costly.
The object of the invention is to provide a simple and inexpensive method of ensuring that the time for the contact connection between a card and a reader/writer is sufficiently long so that a writing cycle that has commenced has time to be completed before the electrical contact with the card is broken when the card is removed from the reader/writer.
The solution to the problem is to prolong the time for the contact connection. According to the invention, this is achieved by the arrangement of a sliding carriage that moves together with the card along the path between the start position and the end position for the card in the reader/writer, whereby the sliding carriage has at least one electrical contact that is brought into contact with an electrical contact on the card during this passage. Following the establishment of an electrical contact connection between the card and reader, connections are coupled so that reading of the card can commence, i.e. reading of the card can begin before the card has reached its end position. At the end position of the card (and the sliding carriage) connections are coupled so that writing on the card can begin.
Further features of the invention are stated in the accompanying claims.